1. Field of the Invention
The present invention relates to a soft mold, and more particularly, to a soft mold having a back-plane attached thereto and a method for fabricating the soft mold. Although the present invention is suitable for a wide scope of applications, it is particularly suitable for a soft mold for forming a fine pattern.
2. Discussion of the Related Art
To fabricate a soft mold, an elastomer is poured into a predetermined mold such that the predetermined mold is formed in one of an intaglio and a relief structure. The soft mold is provided to form a fine pattern for a micro unit. The fine pattern can be a printing pattern, such as intaglio or relief. For example, the soft mold may be used for a color filter layer formed on a color filter substrate of an LCD device, or for an electrode formed in an organic light-emitting diode (OLED). The soft mold may be formed of an elastic polymer, for example, polydimethylsiloxane (PDMS). Polyurethane or polyimide may be used as alternatives to PDMS for the soft mold. Hereinafter, a method for fabricating a soft mold according to the related art will be described with reference to the accompanying drawings.
FIGS. 1A to 1C are cross-sectional views illustrating a method for fabricating a soft mold according to the related art. As shown in FIG. 1A, first, a master mold A for providing a printing patterns, such as intaglio or relief, to a surface of a soft mold is prepared. To form the master mold A, an insulating material layer, such as silicon nitride (Si3N4) or silicon oxide (SiO2) is deposited on an insulating substrate 10, such as a silicon substrate, and then the insulating material layer is patterned by photolithography to form a predetermined pattern 12 on the insulating substrate 10. In the alternative, the predetermined pattern 12 formed on the insulating substrate 10 can be made of metal, photoresist, or wax instead of silicon nitride (Si3N4) or silicon oxide (SiO2).
Referring to FIG. 1B, after fabricating the master mold A, an elastic polymer (elastic elastomer) of prepolymer is poured into the master mold A, to thereby form a prepolymer layer 14. Generally, the elastic polymer is formed of polydimethylsioxane (PDMS). Then, a process for curing the prepolymer layer 14 is performed.
As shown in FIG. 1C, the cured polymer layer becomes a soft mold 16. Then, the soft mold 16 is separated from the master mold (‘A’ of FIG. 1B). Thus, a soft mold of the printing pattern, either intaglio or relief, in the master mold A has been taken. The soft mold may be used in various fields of soft lithography, soft molding, capillary force lithography and in-plane printing.
For long time use of the soft mold in mass production, the soft mold should be durable. In addition, the soft mold should maintain its original shape without shrinkage, expansion or deformation throughout multiple uses. The shape of the soft mold has to be especially maintained if the soft mold is used for in-plane printing for consistency in reproducability.